Terminal block



Jan. 8, 1963 c. c ow-rH 3,072,879

' TERMINAL BLOCK Filed Apr 8 1960 B 2g 38 O3 o NVE Edmond Cf her UnitedStates Patent 3,072,879 TERMINAL BLOCK Edmond C. Crowther, NorthHampton, N.H. Filed Apr. 8, 1960, Ser. No. 21,045 Claims. (Cl. 339-198)This invention relates to an electrical connector for removably securingthe end of a conductor to a workpiece. More specifically, it relates tothose types of connectors which are adapted to be utilized either withwhat are known in the trade as terminal blocks or as an adjunct to busbars.

It is an object of this invention to provide an improved electricalconnector, which will releasably retain the bared end of a conductorwithout physically distorting or damaging same.

Another object of this invention is to provide an electrical connectorhaving excellent conductive qualities but which is simple inconformation and ideally adapted for mass production techniques.

Further objects will become more apparent when the specification is readon the accompanying drawing, where- FIG. 1 is a partial sectional viewof a preferred embodiment of this invention;

FIG. 2 is a partial sectional view of the embodiment shown in FIG. 1,when the connector is in its fully engaged position relative to aconductor;

FIG. 3 is a partial View taken along line 33 of FIG. 1;

FIG. 3A is a perspective view of a plurality of the conuectors shown inFIGS. 1-3 mounted in .a terminal block;

FIG. 4 is a partial sectional elevation of another embodiment of thisinvention;

FIG. 5 is a top view taken along line 55 of FIG. 4.

Referring now to the drawings and specifically FIGS. 1 through 3, theconnector 22 disclosed is a preferred embodiment of the invention and iswell adapted for use with What are known in the trade as terminalblocks. Such a block includes a dielectric base 20 and one or moreproposed connectors 22. In the present instance the base or block 20 isof a molded phenolic resin, as is well known in the art, and is providedwith one or more cavities 66 adapted to accept the connector 22.

In the preferred embodiment, connector 22 includes a cage 24, a screw 26and a spring member 28. The cage 24 is a metallic conductor and can bemanufactured as a sheet metal stamping. It includes a polygonal base 30,which in this embodiment is square at one end as at 3-2 connected to areduced in width portion 34 at the opposite end. A threaded aperture '36is located centrally of the square end 32 and is adapted totelescopically receive the screw 26.

Extending upwardly from opposite end edges are a pair of walls orflanges 38 and 40, which are substantially perpendicular to the base 30and have a width complemental to the adjacent ends of the base 32 and 34respectively. Extending inwardly from wall 3-8 in spaced relation to thebase 30 is a shoulder means or stop 42, which may, for conservation ofspace and material, be struck out of and bent inwardly from the parentmaterial of wall 38. The purpose of this shoulder means 42 will be morethoroughly set forth hereinafter. Extending angularly and laterallyoutwardly from the upper extremity of wall 38, is connector tab orextension 46. Tab 46 is apertured intermediate its length and adapted totelescopically accept a screw 48 which has its free extremity seated inbore 72 within the top of block 20.

Screw 26, which is telescopically associated with the threaded aperture36, has mounted thereon a spring member 28. Spring 28 may be formed fromflat strip stock into a bowed or U-shaped member 28 having a pair of iceopposed apertured arms 52 and 54. Arms 52 and 54 are each provided withan aperture or slot 56 and 58 respectively, which are substantially inregister with one another whereby screw 26 can be telescopicallyassociated therewith. Bight portion 60, which interconnects arms 52 and54, has in its initial condition the form of a semicircle and ispositioned in spaced convex relation to the wall 40. Bight portion 60,in the present instance, is provided with a groove 62, which extendslongitudinally through a substantial portion of its length and opensconcave outwardly towards wall 40, for purposes best set forthhereinafter. The spring member 28 can be rotatably pre-assem-bled toscrew 26 by known means, as for example, by providing an unthreadedportion on the shank of screw 26 adjacent the head and by making theaperture 56 greater than the unthreaded shank portion, but less than thethreaded shank portion, whereby it is axially captured relative to thescrew. Other assembly methods can be utilized, for example, a slot canbe su stituted for aperture 56, and the spring member can he radiallyassociated with the screw. The spring member 26 further can befabricated from strip stock of varying widths, in which the arms 52 and54 are substantially complementary in width to the square end 32 of thepolygonal base 30 and the bight portion 60 being provided with the samewidth as the reduced end 34, for purposes set forth herein after.

To accommodate the connector 22 the block 20 is cored out during itsformation to provide a square bore 66 complementary to the square end 32of the connector and a rectangular bore 68 of lesser width adapted toaccept the reduced end 34 and the bight portion 60'. The upper portionof the block is grooved as at 70 to accept the connector tab 46 andfurther is bored as at 72 to accept the thread cutting connector screw48. It will be noted in FIG. 1 that the square bore 66 has a greaterdepth of penetration than bore 68 to provide a recess for accepting thefree end of screw 26 as it is moved axially downwardly through thethreaded aperture 36.

In the operation of the present device, a conductor 76 is moved axiallybetween the grooved bight portion 60 and the arm 40, which are in spacedopposition to one another. Axial rotary movement of the screw 26 resultsin a closer proximal positioning of arms 52 and 54. This causes alateral movement in the bight portion 60,

towards the arm 40, and produces a deformation of said' bight portion,particularly at its juncture with the side arms 52 and 54, until suchtime as it assumes the substantially flat position shown in FIG. 2. Theconductor 76 is thus securely but releasably captured by the deformedresilient spring. To prevent total collapse or fatigue failure, andpossible release of the wire, shoulder means 42 engages the underside ofupper arm 52 and limits its axial movement.

A second embodiment of the invention is shown in FIGS. 4 and 5, whereinsimilar numerals are utilized to designate similar parts with theaddition of the suffix a. In this embodiment, the cage is basicallyformed by an undercut cavity in the block 20a. The cavity 80 has a base82, which is bored as at 84. Since most of the resinous materials whichare utilized to make the terminal blocks have a low tensile strength, itis often desirable to provide an insert, such as threaded insert 86,adapted to receive the screw 26a. The cavity 80 is further provided withan aperture 88 which comunicates with the upper surface of block 20a.Aperture 88 is much smaller than cavity 80, but is substantially largerthan the head of screw 26a for purposes of access and assembly. Forconvenience in manufacture, block 20a can be made in two parts, 90 and92 respectively, with said two parts being suitably joined by adhesives,by screws, or any other standard method.

A slot 94 communicates with the side of block 2.0a and is aligned withone wall of cavity 80. It is adapted to accept a connector bar 96, whichforms and lines one wall of cavity 80. The outer end of connector 96 isbent to form an apertured flange 97 which is secured to the side wall ofblock a by a suitable screw 98. Screw 98 can be axially moved outwardlyto receive an end of a conductor 100. Mounted on screw 26a is aresilient metallic spring member 280, which, in the present instance,assumes a substantially L-shaped formation. One leg 52a of member 28a isapertured and positioned adjacent the underside of the head of thescrew. Preferably it is rotatively captured on the shank by knownmethods. The second leg or bight portion 69a is bowed outwardly awayfrom the screw shank and is positioned within the cavity 89 so that itis in opposition to bat spaced from connector bar 96, with its lowerfree end 102 abutting the base 82 of the cavity.

A second aperture 104- opens through the top of block 20a andcommunicates with the cavity 30. It is positioned so that itis'substantially in register with the space between bight portion 60aand connector bar 96. In assembling this device, the resilient spring280, which is pre-assembled to the screw 26a, collapses radiallyinwardly toward the screw shank as the sub-assembly is axially insertedthrough the aperture 88. The screw 26a is threaded into the insert 86until the lower free end 183 of spring 28a abuts the base 82.

In the operation of this device, a conductor 75a is inserted downwardlythrough aperture 184 with its free end positioned between the bight 60aand the connector bar 96. Axial movement of the screw 26a into theinsert 86 results in a lateral deformation of the bight portion 60a inthe same fashion as was previously described for the first embodiment.It is possible with the present embodiment to have a completelyinsulated connection by controlling the amount of protruding bared wireand by having the insulation I06 onconductor 76a act as a stop orshoulder means at its terminal point by abutting the upper surface ofblock 2011. Thus, a releasably retained connection is made with acomplete electric circuit between the conductor 76a, connector bar 96,and the terminal connection to wire 100.

It is believed that the present invention has set forth in itsembodiments a simple and efficient connector, capable of being producedby mass production methods and resulting in a simple, economicalfastener, adaptable to a multiplicity of uses.

I am certain that other embodiments of this invention will be apparentto those skilled in the art and it is my intent that I be limited onlyby the appended claims.

I claim:

' 1. A- terminal block for removably retaining a plurality of discreteconductors, including a dielectric base and a plurality of metallicconnectors, said base having a plurality of polygonal shaped boresangularly disposed relative to the top face of said base and openingoutwardly relative to the top face of said base adapted to accept saidconnectors, each of said connectors including a metallic U-shaped cage,a screw, a metallic spring, said cage having an aperture polygonal basecomplementary to and non-rotatably acceptable within one of said bores,a pair of arms extending upwardly from opposite margins of said base,said cage base aperture being adapted to complementarily accept saidscrew in threaded rela tion, said spring initially being a flat bowedstrip having a pair of apertures adjacent opposite free ends which aresubstantially in register when the strip is in its initial bowedcondition, said apertured spring being adapted to be telescopically androtatably assembled with said screw but captured as to axial movement,said bowed spring being substantially U-shaped in spaced opposition toone of said caged arms, the bight portion of said spring adapted to bemoved laterally as the free ends are moved into closer proximalrelationship when the screw is advanced into the threaded aperture, saidbight portion of the spring and the arm with which it is in oppositionbeing of lesser Width than the other arm, said dielectric base borebcing complementary to the narrowed bight and arm, whereby a conductorpositioned between said bight and said arm will be relcasably retainedas the bight is laterally moved and will be restricted against lateralmovement by the narrowed base bore.

2. A device of the type claimed in claim I, wherein shoulder means areprovided on the other arm of the cage, said means extending into thecage in spaced relation to the cage base and adapted to engage theunderside of the upper free end of the spring member, whereby totalcoilapse thereof from compression stress failure is prevented.

3. A device of the type claimed in claim 1, wherein laterally extendingapertured tab means is angularly attached to the other arm of said cage,screw connector means traversing the aperture in said tab, a threadedbore in said dielectric base adapted to accept said screw connector tosecure said tab to said dielectric base.

4. A device of the type claimed in claim 1 having a U-shaped sheet metalcage adapted to be complementary to said cavity including an aperturedbase and upstanding arms cooperatively engaged with said sidewalls, oneof said arms being the conductive means in opposition to said springmeans, the other of said arms being joined at its free end by alaterally extending conductive tab means, said tab means having meansfor connection to a second conductor, screw engaging means surroundingthe aperture in said cage base, means extending from said other armintermediate its length toward the first arm and adapted to engage theunderside of the screw head to limit the axial compression of the springarm.

. 5. A device of the type claimed in claim 4 wherein said cage andcavity are angularly disposed relative to the top of said dielectricbase to facilitate insertion of said conductor, said tab being paralleland in juxtaposition to the top of said dielectric member, said base ofthe cage having a substantially square portion including said threadedaperture and a reduced Width portion from whence the first arm extends,the bight portion of said spring having a width complementary to saidreduced base portion and acceptable within the restricted portion ofsaid cavity.

References Cited in the file of this patent UNITED STATES PATENTS1,531,816 Russell Mar. 31, 1925 1,635,256 Carter July 12, 1927 2,906,990Cain et a1 Sept. 29, 1959 2,953,771 Kussy Sept. 20, 1960 2,957,157Carter Oct. 28, 1960 2,988,726 Agron et al. June 13, 1961 FOREIGNPATENTS 336,612 Great Britain Oct. 16, 1930

1. A TERMINAL BLOCK FOR REMOVABLY RETAINING A PLURALITY OF DISCRETECONDUCTORS, INCLUDING A DIELECTRIC BASE AND A PLURALITY OF METALLICCONNECTORS, SAID BASE HAVING A PLURALITY OF POLYGONAL SHAPED BORESANGULARLY DISPOSED RELATIVE TO THE TOP FACE OF SAID BASE AND OPENINGOUTWARDLY RELATIVE TO THE TOP FACE OF SAID BASE ADAPTED TO ACCEPT SAIDCONNECTORS, EACH OF SAID CONNECTORS INCLUDING A METALLIC U-SHAPED CAGE,A SCREW, A METALLIC SPRING, SAID CAGE HAVING AN APERTURE POLYGONAL BASECOMPLEMENTARY TO AND NON-ROTATABLY ACCEPTABLE WITHIN ONE OF SAID BORES,A PAIR OF ARMS EXTENDING UPWARDLY FROM OPPOSITE MARGINS OF SAID BASE,SAID CAGE BASE APERTURE BEING ADAPTED TO COMPLEMENTARILY ACCEPT SAIDSCREW IN THREADED RELATION, SAID SPRING INITIALLY BEING A FLAT BOWEDSTRIP HAVING A PAIR OF APERTURES ADJACENT OPPOSITE FREE ENDS WHICH ARESUBSTANTIALLY IN REGISTER WHEN THE STRIP IS IN ITS INITIAL BOWEDCONDITION, SAID APERTURED SPRING BEING ADAPTED TO BE TELESCOPICALLY ANDROTATABLY ASSEMBLED WITH SAID SCREW BUT CAPTURED AS TO AXIAL MOVEMENT,SAID BOWED SPRING BEING SUBSTANTIALLY U-SHAPED IN SPACED OPPOSITION TOONE OF SAID CAGED ARMS, THE BIGHT PORTION OF SAID SPRING ADAPTED TO BEMOVED LATERALLY AS THE FREE ENDS ARE MOVED INTO CLOSER PROXIMALRELATIONSHIP WHEN THE SCREW IS ADVANCED INTO THE THREADED APERTURE, SAIDBIGHT PORTION OF THE SPRING AND THE ARM WITH WHICH IT IS IN OPPOSITIONBEING OF LESSER WIDTH THAN THE OTHER ARM, SAID DIELECTRIC BASE BOREBEING COMPLEMENTARY TO THE NARROWED BIGHT AND ARM, WHEREBY A CONDUCTORPOSITIONED BETWEEN SAID BIGHT AND SAID ARM WILL BE RELEASABLY RETAINEDAS THE BIGHT IS LATERALLY MOVED AND WILL BE RESTRICTED AGAINST LATERALMOVEMENT BY THE NARROWED BASE BORE.